Is it a lap-phone? A cellbook? A webtop? Motorola's Atrix 4G smartphone defies classification.

The Atrix is an Android 2.2-powered smartphone that can be docked to a notebook-computer-like keyboard and screen called the Lapdock, which connects to all your virtual office assets online. The Atrix Lapdock, while nowhere near a legitimate notebook PC in terms of speed and performance, offers a surprisingly work-savvy mobile web experience.

The full-size keyboard is almost absurdly luxurious by mobile computing standards. Access speed online is reasonable, as long as you don’t expect blazing broadband speeds (uploads, in particular, are slow). Best of all, the combined system is blissfully light--about three pounds for the phone, Lapdock and power cords. That's probably less than your empty luggage.

You will miss PC niceties like an on-board disc drive. And be warned: AT&T, the exclusive provider of the Atrix for now, is still struggling to roll out its 4G networks nationally. The Atrix ($199 for phone alone or $499 with Lapdock and a two-year contract with AT&T) is really more a powerful 3G mobile tool than a legit mobile broadband appliance. But however you define it, the notion of portable small-business computing will never be the same.